/// <summary>Accept and process web socket.</summary>
/// <param name="context">The context.</param>
/// <param name="client"> The client.</param>
/// <returns>An asynchronous result.</returns>
private async Task AcceptAndProcessWebSocket(
HttpContext context,
WebsocketClientInformation client)
{
// prevent WebSocket errors from bubbling up
try
{
// accept the connection
using (var webSocket = await context.WebSockets.AcceptWebSocketAsync().ConfigureAwait(false))
{
// register our client
WebsocketManager.RegisterClient(client);
// create a cancellation token source so we can cancel our read/write tasks
CancellationTokenSource processCancelSource = new CancellationTokenSource();
// link our local close with the application lifetime close for simplicity
CancellationToken cancelToken = CancellationTokenSource.CreateLinkedTokenSource(
_applicationStopping,
processCancelSource.Token).Token;
Task[] webSocketTasks = new Task[2];
// create send task
webSocketTasks[0] = Task.Run(async() =>
{
try
{
await WriteClientMessages(webSocket, client.Uid, cancelToken).ConfigureAwait(false);
}
finally
{
// **** cancel read if write task has exited ***
processCancelSource.Cancel();
}
});
// create receive task
webSocketTasks[1] = Task.Run(async() =>
{
try
{
await ReadClientMessages(webSocket, client.Uid, cancelToken).ConfigureAwait(false);
}
finally
{
// cancel write if read task has exited
processCancelSource.Cancel();
}
});
// start tasks and wait for them to complete
await Task.WhenAll(webSocketTasks).ConfigureAwait(false);
// close our web socket (do not allow cancel)
await webSocket.CloseAsync(
WebSocketCloseStatus.EndpointUnavailable,
"Connection closing",
CancellationToken.None).ConfigureAwait(false);
}
}
catch (WebSocketException wsEx)
{
// just log for now
Console.WriteLine($" <<< caught exception: {wsEx.Message}");
}
finally
{
WebsocketManager.UnregisterClient(client.Uid);
}
return;
}
